Conventionally, an optical coherence tomography device for dentistry (hereinafter, referred to as an OCT device) divides a laser light emitted from a light source into reference light and measurement light, and irradiates the measurement light to oral tissue from a probe (hand piece) while irradiating the reference light to a reference mirror. Further, the OCT device collects scattered light returning after reflection from the oral tissue by the probe, combines the scattered light and a reflected light from the reference mirror by an optical multiplexer, and analyzes interference light thereof, to generate a tomographic image (for example, see Patent Document 1).
The probe (diagnostic probe portion) of the OCT device described in Patent Document 1 is internally provided with a shutter mechanism for blocking the measurement light by a shutter when performing zero point correction for removing by software noise (image) of image data displayed on a display screen. The zero point correction is to obtain background data in a state of blocking an optical path of the measurement light by closing the shutter, and to obtain a zero point by subtracting the noise generated in the background from measurement data measured by the probe, so that the image is adjusted to appear clearly.
The shutter mechanism is a device for blocking the measurement light sent from a circulator and the scattered light, which is the measurement light reflected from a subject, from passing through the probe. The shutter mechanism is interposed between a collimator lens in a grip portion of the probe and a scanning means in a scanning means housing portion.
Besides the shutter mechanism, as a method of blocking all reflected signals from the subject and creating a state for receiving only a signal from a reference, it is considered to create a state in which a light reflected from the subject does not return by irradiating the measurement light while directing the probe toward the air so that the measurement light does not hit the subject or other objects.